Device for regaining diamond grindings (boart) in diamond grinding



March 7, 1967 L. DE BEER DEVICE FOR REGAINING DIAMOND GRINDINGS (BOARTHNDIAMOND GRINDING Flled June 29, 1964 INVENTOR.

United States Patent 3,307,299 DEVICE FOR REGAINING DIAMOND GRIND- INGS(BOART) IN DIAMOND GRINDING Louis de Beer, N. V. Ahex, Erasmusweg 1077,The Hague, Netherlands Filed June 29, 1964, Ser. No. 379,050 Claims.(Cl. 51270) The invention relates to a device for regaining diamondgrindings (boart) in diamond grinding, comprising a horizontal grindingdisc and a device for catching boart, the latter comprising a fixed fiatring, the inner circular edge whereof fits substantially against thecircumference of the said grinding disc and separates the air flowingoutwardly from the upper and lower face of the said grinding disc fromeach other, and a boart catching filter collar concentrically to saidseparating ring above the upper surface thereof.

In known devices of this type a boart catching collar constitutes a toreshaped space, the underside of which is connected to a conduct fromwhich the air is sucked, by means of a fan, through a filter mass, whichis arranged in a separate container below the grinding table.

In such devices, wherein the air is sucked only locally from thecatching collar, only a small portion of the valuable material can becaught, while moreover the apparatus is made complicated and expensiveby the arrangement of the separate filter container with the fan and itsdriving means.

Especially a device is known wherein the said collar is so high as toproduce hinder to the diamond grinder while laboring. To meet thisdisadvantage the known device shows two opposite interruptions in itscollar for introducing the workpiece holders. Thus, however, aconsiderable portion of the material to be caught is lost, while yet thepossibilities of arranging the holders for the stones to be ground andso also the number of stones which can be treated simultaneously remainrestricted.

The principal object of the present invention is to obtain a device forregaining boart, which is simple and which does not produce any hinderin grinding, and which further will give a high yield in boart caught.

For this purpose, according to the invention, use is made of thephenomenon that a grinding disc which rotates at high speed (about 3000rpm.) produces a stream of air along its circumference in outwarddirection.

Other objects of the invention will appear from the followingdescription which is to be read in connection with the accompanyingdrawing which represents an embodiment of the device.

In the drawing:

FIG. 1 is an axial section through a daimond grinding device, as seen inthe direction of the arrows II in FIG. 2;

FIG. 2 is a view of a grinding device;

FIG. 3 is a sectional view of a detail on an enlarged scale, as seen inthe direction of the arrows III-III in FIG. 2.

In the drawing the axis of the grinding disc is indicated by 1, thegrinding disc by 3 and the connection of the disc and the axis by 2 and2'. The bearings and the driving mechanism of the grinding disc may berealized in the usual manner and are therefore not represented in thedrawing. The grinding disc 3 is arranged in a circular opening 4' of agrinding table 4.

The grinding disc 3 is surrounded by a ring 5, the inner circular edgeof which fits substantially against the circumference of the rotatingdisc.

By the high rotational speed of the grinding disc, which is in practicein the order of 3000 rpm, the air layers immediately above and below thedisc are thrown out-- wardly under the influence of the centrifugalforce produced. In FIG. 1 such air streams at the edge of the disc areindicated by arrows. It will be clear that such air is supplied againfrom above and from below.

The air flow produced at the upper surface of the grinding disc willtake along the diamond particles or boart on the disc surface; the boartsupplied as grinding material as well as the grindings which are takenoff the stones during the treatment.

The catching device comprises a filter unit 6 which is arranged abovethe separating ring 5 in the immediate vicinity of the circumference ofthe grinding disc 3. The ring shaped filter unit 6, the sectional viewwhereof is represented in FIG. 3, may consist of an upper and a lowerbearer ring 7 and 8 respectively, and being connected to the inner edgesof these rings a circular netting 9. Further it may be filled with anysuitable filtering material 10 such as steel wool or several layers ofnetting. The outer circumference of the filter unit may also consist ofnetting material; anyhow it must allow the passage of air.

The filter unit 6 is covered at its upper side by a ring shaped element11. The ring 11 and the filter unit 6 are connected detachably to thegrinding table 3 in a manner to be described below.

The filter unit 6, the separating ring 5 and the cover ring 11constitute a filter collar which is thus lying annularly around the edgeof the grinding disc. The air which is streaming outwardly, under theinfluence of the centrifugal force, with high speed along the wholeupper surface of the disc, conducts the diamond particles immediately tothe filter ring 12, to which a great effective surface and a relativelysmall air resistance can be given, which enables to obtain effectiveregaining of the valuable material without arranging any special suckingdevice. It has appeared that this result can be obtained with a filterunit which projects only over a small distance over the upper surface ofthe grinding disc and of the grinding table. In this way a grinding disc3 remains readily accessible along its whole circumference for thegrinding labor, while a complete view on the work is attained. The coverring 11 serves as a protection for the grinder.

It will further be noted that the centrifugal force on the air is theonly driving medium for the entire boart catching.

The fixed circular plate 5 which fits against the circumference of thegrinding disc 3 prevents the air which is displaced outwardly along theundersurface of the disc to flow upwardly along the outer edge, thiswould disturb the effect which is obtained, because this would make theupper air stream bend so that it would not completely reach the filterunit 12 anymore.

In the embodiment shown, special measures have been taken to providedisappearance of the air behind the filter unit 6 in such a way that theresistance to the air flow is reduced as far as possible. FIG. 1 shows agrinding table 4, the top of which is somewhat lower than the uppersurface of the grinding disc 3. The grinding table supports a plate 18with a central circular opening 18' around the grinding disc member 2',and a plate 19, to which the separating ring 5 is connected, both platesbeing spaced by means of a plurality of guiding members 22, thus leavinga passage for the air thrown outwardly by the grinding disc portionlying below the separating ring 5.

Spaced in relation to plate 13 is a third plate 20 with a circularopening 21, which surrounds the filter unit 6 in the vicinity of theupper outer edge thereof. The plate 20 constitutes the upper surface ofthe grinding table 4, and the space below offers a free passage for theair which has passed the filter unit 6.

Spacing of the plates 19 and 20 may also be obtained by a plurality ofguiding members 23, which, just as the grinding members 22, may have adirection corresponding with the direction of the air stream whenleaving the disc 3.

In order that the boart caught may easily be taken away from the filter6, after several days of working, the filter 6 is executed as adetachable unit, which rests upon the separating ring and is covered bythe ring 11. The ring 11 may be placed upon the filter unit by means ofa hook 12, which corresponds with an opening 13 in the upper ring 7 ofthe filter unit. After a small relative rotational displacement verticaltaking away of the cover ring 11 is prevented, while its rotation andsimultaneously taking away of the filter unit 6 is prevented by means ofa locking mechanism 14. This locking mechanism may be a so calledcylinder lock, arranged in the cover ring 11, and comprising, as isschematically represented in the drawing, a pin member 15, projectingthrough a hole in the filter unit, and c0- operating with a block member16 on the separating ring 5.

In FIG. 1 at the right side, the lock 14' shows the key 17 with theunlocked position, while the left lock 14 shows the locked position.

What I claim is:

1. Device for regaining diamond grindings (boart) in diamond grinding ona grinding mill, comprising a horizontal rotatory grinding disc and adevice for catching boart, the latter comprising a fixed flat ring, theinner circular edge thereof fitting substantially against thecircumference of the said grinding disc and separates the air flowingoutwardly from the upper and lower face of the said grinding disc fromeach other and a boart catching filter collar concentrically to saidseparating ring and above the upper surface thereof, wherein the air,flowing outwardly from the upper surface of the said disc, together withthe diamond particles suspended therein enters rectilinearly, air outletopenings being provided at the outer side of the said filter collar.

2. Device as claimed in claim 1, wherein a flat ring covers the upperside of the filter collar concentrically with the latter along the wholecircumference of the said grinding disc and adjoining the upper surfacethereof, while its inner edge projects slightly further inwardly thanthe filter collar, a gutter shaped filtering space being formed borderedby the said filter collar, the said separating ring, the outer side ofthe said grinding disc and the said covering ring.

3. Device as claimed in claim 1, wherein the entire said boart catchingdevice is arranged exclusively in the region which surrounds thecircumference of the grinding disc.

4. Device as claimed in claim 1, wherein the said air outlet openingsopen into the surrounding air, the difference of pressure on the innerand outer side of the said filter being exclusively obtained from thecentrifugal force on the air produced by the rotation of the grindingdisc mechanism.

5. Device for regaining diamond grindings (boart) in diamond grinding ona grinding mill, comprising a horizontal rotatory grinding disc and adevice for catching boart, the latter comprising a fixed flat ring, theinner circular edge thereof fitting substantially against thecircumference of the said grinding disc and separates the air flowingoutwardly from the upper and lower face of the said grinding disc fromeach other and a boart catching filter collar concentrically to saidseparating ring and above the-upper surface thereof, the said filtercollar being attached to said separating ring so as to form a removableunit with a concentric cover ring, said cover ring being situatedimmediately above the inner edge of a circular opening in a grindingtable in the centre of which the grinding disc is arranged.

6. Device as claimed in claim 5, wherein the said filter unit comprisesat least one ring shaped filter between and attached to an upper and alower bearing ring, a circular netting extending between the said bearerrings, the upper most portion of which is connected to the said coverring.

7. Device as claimed in claim 5, wherein at least one lock member isprovided as a means for removably connecting the said filter unit andthe said cover ring to the grinding table.

8. Device for regaining diamond grindings (boart) in diamond grinding ona grinding mill, comprising a horizontal rotatory grinding disc and adevice for catching boart, the latter comprising a fixed flat ring, theinner circular edge thereof fitting substantially against thecircumference of the said grinding disc and separates the air flowingoutwardly from the upper and lower face of the said grinding disc fromeach other and a boart catching filter collar concentrically to saidseparating ring and above the upper surface thereof and wherein agrinding ing table contains at least one passageway for air, whichpassageway is connected to the space at the outer circumference of saidfilter above said separating ring, and further at least one passagewayfor air, which is connected to the space below said separating ring.

9. Device as claimed in claim 8, wherein the upper portion of the saidgrinding table comprises one platelike member which is provided with acentral circular opening registering with said separating ring andspaced with respect to the lower portion of the said grinding table soas to form a passage for the air which is flowing outwardly by rotationof the grinding disc portion situated below said separating ring, and anupper similar plate-like member with a central circular opening whichregisters with the outer circumference of the filter in the vicinity ofthe upper edge thereof, and being spaced with respect to the firstmentioned plate-like member to form a passage for the air which haspassed the filter in outward direction under influence of the rotationof the grinding disc portion situated above said separating ring.

10. Device as claimed in claim 9, wherein both the passageways for theair above and below the separating ring contain a plurality of guidingmembers for the air stream in a direction corresponding with thedirection of the air stream when leaving the grinding disc.

References Cited by the Examiner UNITED STATES PATENTS 2,715,306 8/1955Roos 51 270 2,720,067 10/ 1955 Yehuda 51-270 2,725,696 12/1955 Roos5.1-27O 2,814,171 11/1957 Bogart 51-273 HAROLD D. WHITEHEAD, PrimaryExamin

1. DEVICE FOR REGAINING DIAMOND GRINDINGS (BOART) IN DIAMOND GRINDING ONA GRINDING MILL, COMPRISING A HORIZONTAL ROTATORY GRINDING DISC AND ADEVICE FOR CATCHING BOART, THE LATTER COMPRISING A FIXED FLAT RING, THEINNER CIRCULAR EDGE THEREOF FITTING SUBSTANTIALLY AGAINST THECIRCUMFERENCE OF THE SAID GRINDING DISC AND SEPARATES THE AIR FLOWINGOUTWARDLY FROM THE UPPER AND LOWER FACE OF THE SAID GRINDING DISC FROMEACH OTHER AND A BOART CATCHING FILTER COLLAR CONCENTRICALLY TO SAIDSEPARATING RING AND ABOVE THE UPPER SURFACE THEREOF, WHEREIN THE AIR,FLOWING OUTWARDLY FROM THE UPPER SURFACE OF THE SAID DISC, TOGETHER WITHTHE DIAMOND PARTICLES SUSPENDED THEREIN ENTERS RECTILINEARLY, AIR OUTLETOPENINGS BEING PROVIDED AT THE OUTER SIDE OF THE SAID FILTER COLLAR.